A clamp-in type valve, which is conventionally used with tubeless tires, particularly on lorries or other heavy goods vehicles consists of a valve stem with a flange at one end, the stem being externally threaded at that end, a rubber grommet having a flange abutting the flange of the valve stem, a ring washer and a nut which is to be screwed onto the threaded stem to clamp the valve in position. The valve stem without the ring washer or nut is inserted from inside the wheel through an aperture in the wheel rim so that the flange on the grommet is trapped between the edge of the rim aperture and the flange on the valve stem, the latter being larger than the aperture. The ring washer is replaced and the nut is then threaded onto the stem from the outside of the wheel and screwed down so that the grommet, which projects from the aperture on the outside is compressed to seal the valve in the aperture and the valve stem is securely clamped in.
If the valve stem becomes damaged the stem can be replaced by unscrewing the nut to release the stem but the stem then has to be withdrawn from the aperture from the inside of the wheel rim, so that the tire has to be stripped from the wheel in order to get access to the inside.